Purpose of while(1); statement in C
What purpose does while(1); serve ? I am aware while(1) (no semicolon) loops infinitely and is similar to a spinlock situation. However I do not see where while(1); could be used ?
Sample code
if(!condition)
{
while(1);
}
Note: This is not a case of do-while() or plain while(1).
Answer
Please note that all valid statements of the language do not have to serve a purpose. They are valid per the grammar of the language.
One can build many similar "useless" statements, such as if (1);.
I see such statements as the conjunction of a conditional (if, while, etc.) and the empty statement ; (which is also a valid statement although it obviously serves no specific purpose).
That being said, I encountered while (1); in security code. When the user does something very bad with an embedded device, it can be good to block them from trying anything else.
With while (1);, we can unconditionally block a device until an accredited operator manually reboots it.
while(1); can also be part of the implementation of a kernel panic, although a for(;;) {} loop seems to be a more common way of expressing the infinite loop, and there might be a non-empty body (for instance to panic_blink()).